Apparatus for protecting bearings and lubrication system



June 21, 1960 L. J. FULLER 2,941,852

APPARATUS FOR PROTECTING BEARINGS AND LUBRICATION SYSTEM Original FiledMarch 4, 1955 1 izigkzzm 40 v TTORNEYS.

FOR rnorncrnsn BEARINGS AND LUBRICATION SYSTEM Lawrence]. Fuller, Box124, R1). 1, Norristown, Pa.

Original application Mar. 4, 1955, Ser. No. 492,280. Divided and thisapplication May 28, 1956, Ser. No. 587,740

APPARATUS 5 Claims. (Cl. 308- -187.1)

turbines a second shaft is provided connected only to the later stagesof the turbine for control of'power outputs The bearings on which theseshafts rotate are the main 7 engine bearings and are vital to thefunctioning of the engine.

volume of air used in the operation of the engine, in view of the factthat the method of sealing the bearings and the bearing lubricationsystem is adequate only for normal conditions and is not satisfactoryunder abnormal conditions in which a high percentage of fine solids arepresent in the entering air.

It will be evident that abnormal conditions, in which a high percentageof air-borne solids are present in the operating gas stream, will existduring cleaning without disassembling in accordance with my copendingUS. patent application, Serial No. 492,280, filed March 4, 1955, forMethod and Apparatus for Cleaning Gas and 'Jet Turbine Engines, nowabandoned, of which the present application is a division. It will alsobe evident that in operating the engine in very dusty conditions, suchas flying through a dust storm, a large amount of air-borne solids inthe operating gas will be encountered.

The present invention has for its principal purpose the provision ofpositive protection for the main bearings and the lubricating systemthereof against contamination by solid particles carried in theoperating gas.

A further purpose of the invention is to create a relativelysuperpressure of clean gas in the vicinity of the bearings and dischargeclean gas through the seals into the operating gas stream, so as toprevent the possibility of flow of operating gas into the vicinity ofthe bearings and the lubrication system. i

A further purpose is to carry the clean gas flow over the shaft and thento permit the clean gas to flow outward to the seals.

Further purposes appear in the specification and in the claims.

The accompanying drawings illustrate two embodiments of rotary engineswhich illustrate the principles of the invention, the forms shown beingchosen largely from the standpoints of convenience in operation andsatisfactory illustration of the principles involved.

Figure 1 is a diagrammatic central longitudinal half sectionillustrating a gas turbine to which the invention has been applied.

Figure 2 is a view similar to Figure 1 illustrating a modification.

Fig. 3 is an enlarged view of the labyrinth seal and also illustratesthe forced lubrication of the bearings.

It is important to protect these bearings'against dirt carried into theengine air compressor by the large I Patented June 21;, 1960 2Describing in illustration but not in limitation and re-- fern'ng to thedrawings:

The rotating parts of gas turbine or other rotating engines as showncomprise an air compressor rotor 41 and a turbine rotor 42 each suitablyrotating on a shaft shown.

at 40. These rotating parts are flanked by a stationary tice have nocontacting surfaces and are not absolutely gas tight, so that gas canflow through such seals; Main bearings are provided at 57, 58, 60 and61.between the shaft 40 and the inner housing portions. The mainbearings are surrounded with oil circulated by any suitable lubricationsystem operating through the inner housing. In order to preventcontamination of the main bearings T: and the lubrication system bysolid particles i passing through the labyrinth seals, I introduce cleangas, such as air, by pipes 63, 64, 65 and 66, from a source 62 which maybe an external source of compressed'air or may be a bleed line carryingair after passing from the air cornpressor through a filter orseparator, and distribute-the clean air to positions within the innerhousing adjacent to the labyrinth seals and in communicationtherewith.It will be evident in Figure 1 that these pipes are located convenientlybetween the bearings and the'labyrinth seals and are capable of buildingup a pressure of clean gas in the inner housing space in excess of theoperating gas pressure so as to maintain a suitably small thoughcontinuous outward gas flow through the seals into the operating gas,thus preventing entrance the seals.

It will be evident that to maintain a suitable gas pressure in theinternal section of the engine which houses the main bearings, it isnecessary to introduce the gas at suffi-' cient volume and pressure tocause outward flow as above described.

While the form of Figure 1 illustrates a practical embodiment of theinvention, it will be evident that in very large engines the diameter ofthe seals may be of the order of several feet and, therefore, thequantity of clean gas required in the embodiment of Figure 1 willnecessarily be quite large.

In the form of Figure 2, shields 67, 68, 70 and 71 are provided whichextend annularly from a position outside the inlet ends of the gas pipesto a position adjacent the outside of the shaft, extending over therotor side of the bearing which is exposed. The shields will preferablyfit close to the rotating shaft. In view of the fact that the diameterat which the shields adjoin the shaft is very small compared to thediameter of the labyrinth seals themselves, it will be evident that arelatively smaller continuous flow of clean gas will be adequate in theform of Figure 2 to protect against contamination of the bearings andthe lubrication system. In the form shown, it will be evident that nolubricant need be present outside the shields.

The main bearings receive additional protection from the lubricatingsystem which forces lubricant through the bearings from the unexposedside to the exposed side of the bearing, where it is drained or pumpedto a suitable cooler and filter as well known before being recirculatedthrough the bearings.

The present invention serves to protect against con of particles throughtamination of thefilter with particles which might collect in the filterandmake it inoperative, and serves to prevent contamination of thelubricant itself, at the same time protecting against damage to thebearings.

By providing positive outward air flow through the labyrinth seals, itwill be evident that. the lubricant remains clean, the size of thefilters can be reduced and filter cartridges will need lessifrequentreplacement.

It will be evident that while the invention has been shown applied tothe entire bearing system of the rotary engine, the principles of theinvention may be applied to any part of: the system, such as the aircompressor, the turbine, or to any part or stage of the turbine asdesired.

While it is preferred in many cases to use air for pro tcction, it willbe evident that any other suitably harmless gas can be employed, such asnitrogen, carbon dioxide, or one of the inert gases such as neon, argonor helium.

It will further be evident that while the invention is illustratedapplied to the geometry of a conventional design or gas turbine, theprinciples of the invention can be modified to meet the requirementsofother arrangements of rotary engine elements as required;

In viewof my invention and disclosure, variations and modifications toobtain all or part of the benefits of my invention without copying thestructure shown will doubtless become evident to-others skilled in theart to meet individual whim or particular need, and I, therefore claimall such insofar as they fall within the reasonable spirit and scopeofmy claims.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

'1. A gas turbine type of engine having a supporting housing, arotatable shaft having rotor means mounted thereon forming a highpressure gas-passage with said housing, bearings having antifrictionelements supporting said shaft and rotor means in said housing, alabyrinth seal between said rotor and said supporting housing to sealsaid gas passage from said housing and to permit relative rotation ofsaid housing and said rotor means, a chamber between said seal and saidsupporting bearing, gas supplying conduit means connected directly tosaid chamber and outside said seal, and means for supplying clean gas tosaid conduit means for providing a gas creating a pressure within saidchamber to maintain a first gas flow from said chamber entering thelabyrinth seal on the side adjacent to said chamber and said bearing andpassing through said seal to counteract the flow of gas from said highpressure passage, and a separate second gas flow from said chamberthrough said supporting bearing thereby maintaining the bearing freefrom abrasive contaminants from said high pressure passage.

2. A gas turbine type of engine having a supporting housing, a rotatableshaft having rotor means mounted thereon forming a high pressure gaspassage with said housing, bearings having antifn'ction elementssupporting said shaft and rotor means in said housing, a labyrinth sealbetween said rotor means and said supporting housing to seal said gaspassage and to permit relative rotation of said housing and said rotor,a chamber between said seal and said supporting bearing, gas supplyingconduit means connected directly to said chamber and outside said seal,a shield extending from between said seal and said conduit means to saidshaft and spaced from said shaft to form a passage therebetween, meansfor supplying clean gas to said conduit for providing a first gas flowbetween said shield and past said bearing and thence through saidpassage to said seal and creating a pressure within said chamber tomaintain a second gas fiow from said chamber through the labyrinth sealon the side adjacent to said chamber and said bearing and passingthrough said seal to counteract the flow of gas from said high pressurepassage, and a separate third gas fiow from said chamber through saidsupporting bearing thereby maintaining the bearing free from abrasivecontaminants from said high pressure passage. i

3. A gas turbine as set forth in claim 1 wherein said labyrinth seal ispositioned at the opposite end of said chamber from said bearing; andsaid conduit means is positionedbetween said seal and said bearing.

4. A gas turbine as set forth in claim 3 wherein a shield extends frombetween said seal and said conduit means, and past said conduit means tosaid shaft to guide the gas flow past said bearing before passingthrough said labyrinth seal.

5. A gas turbine as set forth in claim 1 wherein said labyrinth seal andsaid bearing form the sole means for the" passage of gas from saidchamber;

Buck et al Apr. 13, 1948 Craig et al July 6, 1954

